AOBPreview published online on June 30, 2009
Annals of Botany, doi:10.1093/aob/mcp154
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Effects of pollination timing on seed paternity and seed mass in Silene latifolia (Caryophyllaceae)
University of Lausanne, Department of Ecology and Evolution, CH-1015 Lausanne, Switzerland
* For correspondence. E-mail giorgina.bernasconi{at}unine.ch
Received: 18 February 2009 Returned for revision: 21 April 2009 Accepted: 26 May 2009
Background and Aims: Competition among genetically different pollen donors within one recipient flower may play an important role in plant populations, increasing offspring genetic diversity and vigour. However, under field conditions stochastic pollen arrival times may result in disproportionate fertilization success of the first-arriving pollen, even to the detriment of the recipient plant's and offspring fitness. It is therefore critical to evaluate the relative importance of arrival times of pollen from different donors in determining siring success.
Methods: Hand pollinations and genetic markers were used to investigate experimentally the effect of pollination timing on seed paternity, seed mass and stigmatic wilting in the the dioecious plant Silene latifolia. In this species, high prevalence of multiply-sired fruits in natural populations suggests that competition among different donors may often take place (at fertilization or during seed development); however, the role of variation due to pollen arrival times is not known.
Key Results: First-arriving pollen sired significantly more seeds than later-arriving pollen. This advantage was expressed already before the first pollen tubes could reach the ovary. Simultaneously with pollen tube growth, the stigmatic papillae wilted visibly. Individual seeds were heavier in fruits where one donor sired most seeds than in fruits where both donors had more even paternity shares.
Conclusions: In field populations of S. latifolia, fruits are often multiply-sired. Because later-arriving pollen had decreased chances of fertilizing the ovules, this implies that open-pollinated flowers often benefit from pollen carry-over or pollinator visits within short time intervals, which may contribute to increase offspring genetic diversity and fitness.
Key words: Reproduction, reproductive success, pollen, siring success, microsatellite DNA, paternity, pollen tube growth, seed mass, Silene alba, stigma wilting
Present address: University of Neuchâtel, Institute of Biology, Rue Emile-Argand 11, CH-2009 Neuchâtel, Switzerland.
Present address: Department of Biological Sciences, 2500 University Drive N.W., University of Calgary, Calgary AB Canada T2 N 1N4.
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